Abu Musa sought permission to enter upon Umar three times, but he was not granted permission, so he left. Umar later met him and asked, "What made you turn back?"Abu Musa replied, "I heard the Messenger of Allah ﷺ say, 'Whoever seeks permission three times and is not granted it should return.'"Umar said, "You must bring me proof of this, or I will deal with you severely."So Abu Musa went to the gathering of his people and implored them by Allah. I said, "I will go with you." They testified on his behalf, and Umar let him go.
حدثنا يزيد بن هارون قال أخبرنا داود عن أبي نضرة
استأذن أبو موسى على عمر رضي الله تعالى عنه ثلاثا فلم يؤذن له فرجع فلقيه عمر رضي الله تعالى عنه فقال ما شأنك رجعت قال سمعت رسول الله ﷺ يقول من استأذن ثلاثا فلم يؤذن له فليرجع فقال لتأتين على هذه ببينة أو لأفعلن ولأفعلن فأتى مجلس قومه فناشدهم الله تعالى فقلت أنا معك فشهدوا له فخلى سبيله